Aliphatic polyesters consisting of hydrolytically and/or enzymatically degradable ester bonds in each repeating unit possess diverse thermomechanical properties and desired biodegradability and biocompatibility, thus, finding broad applications in biomedical fields. Among them, poly(4-hydroxybutyrate) (P4HB) is a biomaterial receiving particular attention, due to its proper thermal transition temperatures (T_g ∼ – 50 °C, T_m ∼ 60 °C) relative to the environment of living systems, excellent mechanical properties (high toughness and extensibility when molar mass is sufficiently high), and facile degradability in aqueous media where living systems function. The production of P4HB has long relied on biological fermentation, where it is stored in fermented cells and extracted at the end of the fermentation. However, the high production cost of the fermentation process, associated with its slow reaction kinetics and presently limited production volume, hinders broader implementations of P4HB. In addition, biological routes typically produce P4HB with poor control over the polymer molar mass and dispersity, and postfermentation treatment is employed to offer various molar mass P4HB formulations. Considering that chemical catalysis generally offers faster reaction kinetics, more rapid catalyst tuning, a higher degree of control, and better scalability, it would be desirable to develop a chemocatalytic route to access P4HB more rapidly, at scale, and on-demand for tailorable chain lengths and architectures. In this context, developing the effective and efficient chemocatalytic synthesis of P4HB through ring-opening polymerization (ROP) of γ-butyrolactone (γBL), which is bioderived and available at scale, is of great interest and significance.

中文翻译：

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化学合成 P4HB：从“不可聚合”单体到高性能生物材料的十年历程


脂肪族聚酯由每个重复单元中的可水解和/或酶促降解的酯键组成，具有不同的热机械性能和所需的生物降解性和生物相容性，因此在生物医学领域有广泛的应用。其中，聚（4-羟基丁酸酯）（P4HB）是一种受到特别关注的生物材料，因为它相对于生命系统环境具有适当的热转变温度（T_g ∼ – 50 °C，T _m ∼ 60 °C），优异的机械性能（当摩尔质量足够高时具有高韧性和延展性），以及在生命系统运作的水性介质中易于降解。长期以来，P4HB 的生产一直依赖于生物发酵，将其储存在发酵细胞中，并在发酵结束时提取。然而，发酵过程的高生产成本，加上其缓慢的反应动力学和目前有限的产量，阻碍了 P4HB 的更广泛实施。此外，生物途径通常产生 P4HB，对聚合物摩尔质量和分散性控制不佳，并且采用发酵后处理提供各种摩尔质量 P4HB 配方。考虑到化学催化通常提供更快的反应动力学、更快速的催化剂调整、更高程度的控制和更好的可扩展性，因此需要开发一种化学催化路线，以更快速、更大规模地、按需获得 P4HB，以实现可定制的链长和结构。在此背景下，通过生物衍生且可大规模获得的 γ-丁内酯 （γBL） 的开环聚合 （ROP） 开发有效且高效的 P4HB 化学催化合成具有极大的兴趣和意义。